How find entities by many to many relation entity id

Question

I have tags and articles entities that linked by many to many. How can I find tags if I know article id?

@Entity("articles")
class ArticleEntity {
  @ManyToMany(() => TagEntity, tag => tag.articles)
  @JoinTable()
  tags: TagEntity[];
}

@Entity("tags")
class TagEntity {
  @ManyToMany(() => ArticleEntity, article => article.tags)
  articles: ArticleEntity[];
}

const articleId = 1;
this.tagRepo.find({ where: { articles: { id: articleId } } }); // ??

Answer 1

1. To load articles with tags you must specify relation in FindOptions

const articleId = 1;
const article = await connection.getRepository(ArticleEntity)
             .findOne(articleId, {relations: ["tags"]});

console.log(article.tags); // contains all tags related to the article.id = 1

2. Using QueryBuilder you can join them

const article = await connection
    .getRepository(ArticleEntity)
    .createQueryBuilder("articles")
    .leftJoinAndSelect("articles.tags", "tags")
    .where({ id: articleId })
    .getMany();

console.log(article.tags);